Innate immune evasion of Escherichia coli clinical strains from orthopedic implant infections.

Escherichia coli is one of the first causes of Gram-negative orthopedic implant infections (OII). Those infections, usually hematogenous, mostly originate from the urinary tract. We investigated the strategies developed by E. coli in this context to evade host innate immune responses, i.e. complement and polymorphonuclear neutrophils (PMN). Twenty strains from OII were compared with 20 strains from bacteremia in patients with non-infected orthopedic implant. In both groups, 6/20 (30 %) strains lysed PMNs, due to the production of the pore-forming toxin α-hemolysin (HlyA). For the others, resistance to phagocytic killing by PMN was not significantly different between both groups. In contrast, resistance to complement-mediated serum killing was significantly higher in OII strains than in the others (65 % vs 10 %; P <0.001). In E. coli, different mechanisms have been involved in complement resistance. Here, serum resistance was not linked to a group 2 capsule, or a loss of outer membrane permeability, or the recruitment of the complement inhibitor C4bp, but was significantly associated with the synthesis of long-chain LPS, regardless of the O-antigen. Thus, serum resistance could promote seeding of peri-implant tissues by helping E. coli to either persist in blood and reach the site of infection or overcome localized complement activation.

A layered model of a virtual human intestine for surgery simulation.

In this paper, we propose a new approach to simulate the small intestine in a context of laparoscopic surgery. The ultimate aim of this work is to simulate the training of a basic surgical gesture in real-time: moving aside the intestine to reach hidden areas of the abdomen. The main problem posed by this kind of simulation is animating the intestine. The problem comes from the nature of the intestine: a very long tube which is not isotropically elastic, and is contained in a volume that is small when compared to the intestine's length. It coils extensively and collides with itself in many places. To do this, we use a layered model to animate the intestine. The intestine's axis is animated as a linear mechanical component. A specific sphere-based model handles contacts and self-collisions. A skinning model is used to create the intestine's volume around the axis. This paper discusses and compares three different representations for skinning the intestine: a parametric surface model and two implicit surface models. The first implicit surface model uses point skeletons while the second uses local convolution surfaces. Using these models, we obtained good-looking results in real-time. Some videos of this work can be found in the online version at doi: 10.1016/j.media.2004.11.006 and at www-imagis.imag.fr/Publications/2004/FLAMCFC04.

Lethal effects of mexel 432, an antifouling agent, on embryolarval development of common carp (Cyprinus carpio L.).

Embryolarval lethal effects of Mexel 432, an antifouling agent, were determined in the laboratory during continuous exposure, beginning at fertilization, under various experimental conditions in eight different spawns of the common carp (Cyprinus carpio L). In synthetic water at 24 degrees C and without larval feeding, correlations between LC50 values and the various experimental conditions tested, except Mexel 432 concentration, were low. The mean LC50 values were 1.13+/-0.35 mg/liter after 3 days of exposure and 0.88+/-0.36 mg/liter after 7 days. In five spawns, it was 0. 69+/-0.32 mg/liter after 9 days. The lowest and highest LC50 values were 0.34 and 1.58 mg/liter after 7 days of exposure. Sensitivity to Mexel 432 increased slightly from the egg to the newly hatched larva and the developed larva. No lethality was observed during a period of recuperation after 4 days of exposure. The toxicity of Mexel 432 was not strongly reduced after 15 days of conservation of the solution. Vessel walls pretreated with Mexel 432 revealed no toxicity by contact or after eventual desorption. Methodological endpoints such as criteria for spawn quality, experimental conditions for the tests, demonstration of cumulative effects, and toxicometric importance of the period of mortality by starvation in fish early life toxicity tests are discussed.

[SPIC: a training simulator for coelioscopic interventions with gynecologic purpose]. / SPIC: simulateur pédagogique d'interventions coelioscopiques à visée gynécologique.

There is much demand for laparoscopy training. We have developed a training simulator for initial training in gynecological laparoscopy. The simulator includes a mannequin with 3 located trocars, a PC and software for managing the graphical part of the training protocol. The objective is to learn how to achieve spatial localization and handle tools within the abdominal cavity. A series of exercises are proposed with increasing degree of difficulty. The simulator can be customized to simulate many different scenarios. The trainer must be present to provide an ultimate assessment of the trainee's experience. This new training tool cannot replace traditional surgical training but can help make it more efficient. The simulator is now being used by residents. Further technical developments are in progress to add further indispensable mechanical interactions (force feed back) to visualize the organ deformations and organ dissections within the abdominal cavity.

Deltamethrin multifactorial activity toward carp larva mobility related to calcium, humic acids, and pH.

The toxicity of pyrethroid insecticide deltamethrin was assessed by the "escaping capability" of carp larvae out of a trap. Mobility was tested after 1, 4, and 12 hr exposure to eight deltamethrin concentrations in standard water and after 24 hr exposure to seven deltamethrin concentrations in 18 media derived from the combinations of pH levels of 6.9, 7.8, 9.0, calcium concentrations of 2 . 10(-4) and 2 . 10(-2) M, and humic acid concentrations on 0, 5 and 100 mg/liter. In standard water, a 1-hr exposure at 4 microg/liter deltamethrin increased the mobility, while a 4-hr 32 microg/liter exposure decreased it. After 24 hr without deltamethrin, mobility was reduced at pH 6.9 and 7.8 and 2 . 10(-4) M calcium. It was also reduced in 100 mg/liter humic acids, especially when the former pH and calcium conditions were used. Humic acid effects could partly result from a calcium concentration reduction in water, and darkness due to humic acid coloration could play a minor role. Increasing humic acid concentration, calcium concentration, and pH reduced deltamethrin activity. In 0 or 5 mg/liter humic acids the No Observed Effect Concentration was 1 microg/liter, and in 100 mg/liter humic acid it was 2 microg/liter. Compared to previous results on deltamethrin-induced lethality, the escape test appeared less reproducible, but was 2 or 4 times more sensitive.

Deltamethrin lethal multifactorial activity toward carp larva related to pH, calcium, and humic acid concentrations.

Acute 24-hr embryotoxicity of the pyrethroid insecticide delta-methrin toward carp larvae was tested in multifactorial combinations of three pHs (6.9, 7.8, 9.0), two calcium concentrations ([Ca] = 2 x 10(-4) and 2 x 10(-2) M), and three humic acids concentrations ([HA] = 0, 5, and 100 mg/liter). Lethal effects were determined and compared to the distribution and hexane extractibility of radiolabeled deltamethrin in the solution and on the vessel walls, either in the presence or in the absence of the larvae. As a function of the three combined factors tested, the no observed effect concentrations (NOECs) differed to a maximum by a factor of 8, while they differed by only a factor of 2 with pH alone, and by a factor of 4 with calcium or humic acids alone. No contact toxicity was observed with adsorbed deltamethrin on the vessel walls, on which adsorption and hexane extractibility was increased in the presence of larvae. The most plausible interpretation for the toxicological influence of the physicochemical factors tested on deltamethrin toxicity deals with the deltamethrin distribution in the medium for humic acids, changes in biological targets for calcium influence, and, for pH influence, degradation speed or one of the two other explanations.

Toxic effects, at three pH levels, of two reference molecules on common carp embryo.

Early life-stage survival, motility, and growth toxicity tests were carried out on common carp (Cyprinus carpio L.) endotrophic embryo, with two reference molecules (captafol and DNOC), from fertilization to the end of the first two-thirds period of mortalities by starvation. Thirteen days duration exposure was performed in daily renewed medium, at 24.5 degrees C, in standard synthetic water, at three pHs (6.9, 7.8, 9.0), in the presence of 10 mM/liter nontoxic pH buffer. Nominal concentrations of toxicants were 0.0, 0.25, 0.5, 1.0, and 2.0 mg/liter. Toxic effects on survival, motility, and growth decreased with increasing pH. From pH 6.9 to 9.0, the "no-observed-effect concentrations" differed by a factor greater than 8. Motility and growth cannot be considered, at population level, as true sublethal embryo-larval toxicity criteria. The toxicological interpretation of these results is discussed. They confirm the need of multifactorial methods for toxic risks and effects assessment on fish early life stages in the environment.

Simulator for laser photocoagulation in ophthalmology.

The practice of laser photocoagulation plays a major role in the ocular therapy, but the persistence of many postoperative complications denotes genuine difficulty in mastering the technique. The authors present a device which, thanks to the use of simulation, enables actual practice to be dissociated from apprenticeship. While complying with the constraints of realism with regard to habitual conditions of laser use, the device offers access to a wide variety of clinical situations. The apparatus is built around the traditional instrument. A virtual image of the fundus is produced in real time from the sensors which detect the actual gestures used. The calculations make use of textured geometrical models. Digitized color photographs are organized to form a database which reflects the diversity of pigmentations and pathologies. A software interface has been developed to facilitate the use of the device. The prototype is operated using a PC-compatible computer; it displays the images at the rate of at least seven per second on a miniature CGA screen incorporated in the slit-lamp. It is currently being validated for clinical applications. Above and beyond apprenticeship in laser photocoagulation, its potential applications extend to the entire field of ophthalmogical symptomatology and, more broadly, to the simulation of any examination conducted with the help of binocular or endoscopic optics.

[SOPHOCLE (Ophthalmologic Simulator of Laser PHOtocoagulation): contribution to virtual reality]. / SOPHOCLE (Simulateur Ophtalmologique de PHOtoCoagulation LaSer): contribution de la réalité virtuelle.

PURPOSE: This study was undertaken to teach laser retinal photocoagulation in different disorders using a "virtual eye". Most ophthalmologists routinely use laser photocoagulator. Both indications and laser effects are well-known. However, in various diseases (diabetic retinopathy, age-related-macular degeneration, myopia...) complications rate increase or at least does not decrease. The main reasons are: - ignorance of risk factors, - misuse of the instrument. METHODS: We developed a new automated device stimulating a real laser photocoagulator. Only slit-lamp exists. The three-mirror lens, the fundus and the retinal photocoagulation impacts are "virtual". CONCLUSION: The aim of the simulator is to help practitioners to recognize various pathologies almost as in real conditions and to be familiar with different technics of photocoagulation. By using computer assisted learning, a constant evaluation determines the level and the progress of practitioners.

Stabilization of oversaturated aqueous solutions of deltamethrin, a highly lipophilic molecule.

The stability of oversaturated solutions of the highly lipophilic molecule deltamethrin under the conditions of continuous agitation and oxygenation by air bubble flow in a toxicologic test on fish embryos was studied. In polyethylene, glass, and Teflon containers, the 24-hr adsorption rate of 1 mg/l solutions was over 80%. Improvement by Sharon and Solomon's PEG-glass pretreatment did not exceed a small percentage. After agarose precoating, the adsorption rate in the glass or polyethylene containers was reduced to about 20%. The stabilizing effect of precoating agarose containers diminished with the concentration of the solution.

[Influence of light conditions and the presence of a laying substratum on ovarian function of virgin female Hydrellia griseola Fall. (Diptera, Ephydridae)]. / Influence des conditions d'éclairement et de la présence d'un substrat de ponte sur le fonctionnement ovarien des femelles vierges d'Hydrellia griseola Fall. (Diptère ephydridae)

None or very few eggs are deposited by young virgin Hydrellia griseola when exposed to constant darkness or deprived of any ovipositional substrate. Ovaries of such females have been investigated in order to find out what happens with the matured eggs. Under suitable conditions (photoperiodic regime and host-plant provided), oviposition occurs only over a fixed level of congestion of the ovaries. Under constant darkness there is neither accumulation nor deficiency in mature eggs. The withholding of the ovipositional substrate induces their accumulation in the ovarioles. In both cases, less eggs are produced. The alteration of the efficiency of the ovaries resulting from an important or complete reduction of oviposition takes different forms, depending on which stimulus is cut off.